Class: Brakeman::AliasProcessor

Inherits:
SexpProcessor show all
Includes:
CallConversionHelper, ProcessorHelper, SafeCallHelper, Util
Defined in:
lib/brakeman/processors/alias_processor.rb

Overview

Returns an s-expression with aliases replaced with their value. This does not preserve semantics (due to side effects, etc.), but it makes processing easier when searching for various things.

Constant Summary collapse

ARRAY_CONST =
s(:const, :Array)
HASH_CONST =
s(:const, :Hash)
RAILS_TEST =
s(:call, s(:call, s(:const, :Rails), :env), :test?)
STRING_NEW =
s(:call, s(:const, :String), :new)

Constants included from CallConversionHelper

CallConversionHelper::STRING_LENGTH_LIMIT

Constants included from Util

Util::ALL_COOKIES, Util::ALL_PARAMETERS, Util::COOKIES, Util::COOKIES_SEXP, Util::DIR_CONST, Util::LITERALS, Util::PARAMETERS, Util::PARAMS_SEXP, Util::PATH_PARAMETERS, Util::QUERY_PARAMETERS, Util::REQUEST_COOKIES, Util::REQUEST_ENV, Util::REQUEST_PARAMETERS, Util::REQUEST_PARAMS, Util::REQUEST_REQUEST_PARAMETERS, Util::SAFE_LITERAL, Util::SESSION, Util::SESSION_SEXP

Constants inherited from SexpProcessor

SexpProcessor::VERSION

Instance Attribute Summary collapse

Attributes inherited from SexpProcessor

#context, #env, #expected

Instance Method Summary collapse

Methods included from CallConversionHelper

#all_literals?, #join_arrays, #join_strings, #math_op, #process_array_access, #process_hash_access

Methods included from Util

#array?, #block?, #call?, #camelize, #class_name, #constant?, #contains_class?, #cookies?, #dir_glob?, #false?, #hash?, #hash_access, #hash_insert, #hash_iterate, #integer?, #kwsplat?, #literal?, #make_call, #node_type?, #number?, #params?, #pluralize, #rails_version, #regexp?, #remove_kwsplat, #request_env?, #request_value?, #result?, #safe_literal, #safe_literal?, #safe_literal_target?, #set_env_defaults, #sexp?, #string?, #string_interp?, #symbol?, #template_path_to_name, #true?, #underscore

Methods included from ProcessorHelper

#current_file, #process_all, #process_all!, #process_call_args, #process_call_defn?, #process_class, #process_module

Methods inherited from SexpProcessor

#in_context, #process, processors, #scope

Constructor Details

#initialize(tracker = nil, current_file = nil) ⇒ AliasProcessor

Returns a new AliasProcessor with an empty environment.

The recommended usage is:

AliasProcessor.new.process_safely src


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# File 'lib/brakeman/processors/alias_processor.rb', line 23

def initialize tracker = nil, current_file = nil
  super()
  @env = SexpProcessor::Environment.new
  @inside_if = false
  @ignore_ifs = nil
  @exp_context = []
  @tracker = tracker #set in subclass as necessary
  @helper_method_cache = {}
  @helper_method_info = Hash.new({})
  @or_depth_limit = (tracker && tracker.options[:branch_limit]) || 5 #arbitrary default
  @meth_env = nil
  @current_file = current_file
  set_env_defaults
end

Instance Attribute Details

#resultObject (readonly)

Returns the value of attribute result


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# File 'lib/brakeman/processors/alias_processor.rb', line 16

def result
  @result
end

#trackerObject (readonly)

Returns the value of attribute tracker


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# File 'lib/brakeman/processors/alias_processor.rb', line 16

def tracker
  @tracker
end

Instance Method Details

#array_detect_all_literals?(exp) ⇒ Boolean

Returns:

  • (Boolean)

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# File 'lib/brakeman/processors/alias_processor.rb', line 736

def array_detect_all_literals? exp
  call? exp and
  [:detect, :find].include? exp.method and
  exp.first_arg.nil? and
  (all_literals? exp.target or dir_glob? exp.target)
end

#array_include_all_literals?(exp) ⇒ Boolean

Check if exp is a call to Array#include? on an array literal that contains all literal values. For example:

[1, 2, "a"].include? x

Returns:

  • (Boolean)

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# File 'lib/brakeman/processors/alias_processor.rb', line 730

def array_include_all_literals? exp
  call? exp and
  exp.method == :include? and
  (all_literals? exp.target or dir_glob? exp.target)
end

#assign_args(method_exp, args, meth_env = SexpProcessor::Environment.new) ⇒ Object


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# File 'lib/brakeman/processors/alias_processor.rb', line 1070

def assign_args method_exp, args, meth_env = SexpProcessor::Environment.new
  formal_args = method_exp.formal_args

  formal_args.each_with_index do |arg, index|
    next if index == 0

    if arg.is_a? Symbol and sexp? args[index - 1]
      meth_env[Sexp.new(:lvar, arg)] = args[index - 1]
    end
  end

  meth_env
end

#collapse_send_call(exp, first_arg) ⇒ Object

Change x.send(:y, 1) to x.y(1)


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# File 'lib/brakeman/processors/alias_processor.rb', line 933

def collapse_send_call exp, first_arg
  # Handle try(&:id)
  if node_type? first_arg, :block_pass
    first_arg = first_arg[1]
  end

  return unless symbol? first_arg or string? first_arg
  exp.method = first_arg.value.to_sym
  args = exp.args
  exp.pop # remove last arg
  if args.length > 1
    exp.arglist = args[1..-1]
  end
end

#duplicate?(exp) ⇒ Boolean

Returns:

  • (Boolean)

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# File 'lib/brakeman/processors/alias_processor.rb', line 1093

def duplicate? exp
  @exp_context[0..-2].reverse_each do |e|
    return true if exp == e
  end

  false
end

#early_return?(exp) ⇒ Boolean

Returns:

  • (Boolean)

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# File 'lib/brakeman/processors/alias_processor.rb', line 813

def early_return? exp
  return true if node_type? exp, :return
  return true if call? exp and [:fail, :raise].include? exp.method

  if node_type? exp, :block, :rlist
    node_type? exp.last, :return or
      (call? exp and [:fail, :raise].include? exp.method)
  else
    false
  end
end

#find_method(*args) ⇒ Object


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# File 'lib/brakeman/processors/alias_processor.rb', line 1101

def find_method *args
  nil
end

#find_push_target(exp) ⇒ Object

Finds the inner most call target which is not the target of a call to <<


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# File 'lib/brakeman/processors/alias_processor.rb', line 1085

def find_push_target exp
  if call? exp and exp.method == :<<
    find_push_target exp.target
  else
    exp
  end
end

#get_call_value(call) ⇒ Object


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# File 'lib/brakeman/processors/alias_processor.rb', line 985

def get_call_value call
  method_name = call.method

  #Look for helper methods and see if we can get a return value
  if found_method = find_method(method_name, @current_class)
    helper = found_method[:method]

    if sexp? helper
      value = process_helper_method helper, call.args
      value.line(call.line)
      return value
    else
      raise "Unexpected value for method: #{found_method}"
    end
  else
    call
  end
end

#get_rhs(exp) ⇒ Object

Handles x = y = z = 1


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# File 'lib/brakeman/processors/alias_processor.rb', line 446

def get_rhs exp
  if node_type? exp, :lasgn, :iasgn, :gasgn, :attrasgn, :safe_attrasgn, :cvdecl, :cdecl
    get_rhs(exp.rhs)
  else
    exp
  end
end

#join_item(item, join_value) ⇒ Object


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# File 'lib/brakeman/processors/alias_processor.rb', line 339

def join_item item, join_value
  if item.is_a? String
    "#{item}#{join_value}"
  elsif string? item or symbol? item or number? item
    s(:str, "#{item.value}#{join_value}")
  else
    s(:evstr, item)
  end
end

#merge_if_branch(branch_env) ⇒ Object


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# File 'lib/brakeman/processors/alias_processor.rb', line 904

def merge_if_branch branch_env
  branch_env.each do |k, v|
    next if v.nil?

    current_val = env[k]

    if current_val
      unless same_value?(current_val, v)
        if too_deep? current_val
          # Give up branching, start over with latest value
          env[k] = v
        else
          env[k] = current_val.combine(v, k.line)
        end
      end
    else
      env[k] = v
    end
  end
end

#meth_envObject


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# File 'lib/brakeman/processors/alias_processor.rb', line 424

def meth_env
  begin
    env.scope do
      set_env_defaults
      @meth_env = env.current
      yield
    end
  ensure
    @meth_env = nil
  end
end

#new_string?(exp) ⇒ Boolean

String.new ?

Returns:

  • (Boolean)

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# File 'lib/brakeman/processors/alias_processor.rb', line 1206

def new_string? exp
  exp == STRING_NEW
end

#only_ivars(include_request_vars = false, lenv = nil) ⇒ Object

Returns a new SexpProcessor::Environment containing only instance variables. This is useful, for example, when processing views.


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# File 'lib/brakeman/processors/alias_processor.rb', line 950

def only_ivars include_request_vars = false, lenv = nil
  lenv ||= env
  res = SexpProcessor::Environment.new

  if include_request_vars
    lenv.all.each do |k, v|
      #TODO Why would this have nil values?
      if (k.node_type == :ivar or request_value? k) and not v.nil?
        res[k] = v.dup
      end
    end
  else
    lenv.all.each do |k, v|
      #TODO Why would this have nil values?
      if k.node_type == :ivar and not v.nil?
        res[k] = v.dup
      end
    end
  end

  res
end

#only_request_varsObject


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# File 'lib/brakeman/processors/alias_processor.rb', line 973

def only_request_vars
  res = SexpProcessor::Environment.new

  env.all.each do |k, v|
    if request_value? k and not v.nil?
      res[k] = v.dup
    end
  end

  res
end

#process_array_join(array, join_str) ⇒ Object

Painful conversion of Array#join into string interpolation


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# File 'lib/brakeman/processors/alias_processor.rb', line 289

def process_array_join array, join_str
  result = s()

  join_value = if string? join_str
                 join_str.value
               else
                 nil
               end

  array[1..-2].each do |e|
    result << join_item(e, join_value)
  end

  result << join_item(array.last, nil)

  # Combine the strings at the beginning because that's what RubyParser does
  combined_first = ""
  result.each do |e|
    if string? e
      combined_first << e.value
    elsif e.is_a? String
      combined_first << e
    else
      break
    end
  end

  # Remove the strings at the beginning
  result.reject! do |e|
    if e.is_a? String or string? e
      true
    else
      break
    end
  end

  result.unshift combined_first

  # Have to fix up strings that follow interpolation
  result.reduce(s(:dstr)) do |memo, e|
    if string? e and node_type? memo.last, :evstr
      e.value = "#{join_value}#{e.value}"
    elsif join_value and node_type? memo.last, :evstr and node_type? e, :evstr
      memo << s(:str, join_value)
    end

    memo << e
  end
end

#process_attrasgn(exp) ⇒ Object

'Attribute' assignment x.y = 1 or x = 1


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# File 'lib/brakeman/processors/alias_processor.rb', line 525

def process_attrasgn exp
  tar_variable = exp.target
  target = process(exp.target)
  method = exp.method
  index_arg = exp.first_arg
  value_arg = exp.second_arg

  if method == :[]=
    index = exp.first_arg = process(index_arg)
    value = exp.second_arg = process(value_arg)
    match = Sexp.new(:call, target, :[], index)

    set_value match, value

    if hash? target
      env[tar_variable] = hash_insert target.deep_clone, index, value
    end

    unless node_type? target, :hash
      exp.target = target
    end
  elsif method.to_s[-1,1] == "="
    exp.first_arg = process(index_arg)
    value = get_rhs(exp)
    #This is what we'll replace with the value
    match = Sexp.new(:call, target, method.to_s[0..-2].to_sym)

    set_value match, value
    exp.target = target
  else
    raise "Unrecognized assignment: #{exp}"
  end
  exp
end

#process_block(exp) ⇒ Object

Start new scope for block.


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# File 'lib/brakeman/processors/alias_processor.rb', line 410

def process_block exp
  env.scope do
    process_default exp
  end
end

#process_bracket_call(exp) ⇒ Object


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# File 'lib/brakeman/processors/alias_processor.rb', line 94

def process_bracket_call exp
  r = replace(exp)

  if r != exp
    return r
  end

  exp.arglist = process_default(exp.arglist)

  r = replace(exp)

  if r != exp
    return r
  end

  t = process(exp.target.deep_clone)

  # sometimes t[blah] has a match in the env
  # but we don't want to actually set the target
  # in case the target is big...which is what this
  # whole method is trying to avoid
  if t != exp.target
    e = exp.deep_clone
    e.target = t

    r = replace(e)

    if r != e
      return r
    end
  else
    t = nil
  end

  if hash? t
    if v = process_hash_access(t, exp.first_arg)
      v.deep_clone(exp.line)
    else
      case t.node_type
      when :params
        exp.target = PARAMS_SEXP.deep_clone(exp.target.line)
      when :session
        exp.target = SESSION_SEXP.deep_clone(exp.target.line)
      when :cookies
        exp.target = COOKIES_SEXP.deep_clone(exp.target.line)
      end

      exp
    end
  elsif array? t
    if v = process_array_access(t, exp.args)
      v.deep_clone(exp.line)
    else
      exp
    end
  elsif t
    exp.target = t
    exp
  else
    if exp.target # `self` target is reported as `nil` https://github.com/seattlerb/ruby_parser/issues/250
      exp.target = process_default exp.target
    end

    exp
  end
end

#process_call(exp) ⇒ Object

Process a method call.


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# File 'lib/brakeman/processors/alias_processor.rb', line 166

def process_call exp
  return exp if process_call_defn? exp
  target_var = exp.target
  target_var &&= target_var.deep_clone
  if exp.node_type == :safe_call
    exp.node_type = :call
  end

  if exp.method == :[]
    return process_bracket_call exp
  else
    exp = process_default exp
  end

  #In case it is replaced with something else
  unless call? exp
    return exp
  end

  target = exp.target
  method = exp.method
  first_arg = exp.first_arg

  if method == :send or method == :try
    collapse_send_call exp, first_arg
  end

  if node_type? target, :or and [:+, :-, :*, :/].include? method
    res = process_or_simple_operation(exp)
    return res if res
  elsif target == ARRAY_CONST and method == :new
    return Sexp.new(:array, *exp.args)
  elsif target == HASH_CONST and method == :new and first_arg.nil? and !node_type?(@exp_context.last, :iter)
    return Sexp.new(:hash)
  elsif exp == RAILS_TEST
    return Sexp.new(:false)
  end

  #See if it is possible to simplify some basic cases
  #of addition/concatenation.
  case method
  when :+
    if array? target and array? first_arg
      exp = join_arrays(target, first_arg, exp)
    elsif string? first_arg
      exp = join_strings(target, first_arg, exp)
    elsif number? first_arg
      exp = math_op(:+, target, first_arg, exp)
    end
  when :-, :*, :/
    exp = math_op(method, target, first_arg, exp)
  when :[]
    if array? target
      exp = process_array_access(target, exp.args, exp)
    elsif hash? target
      exp = process_hash_access(target, first_arg, exp)
    end
  when :merge!, :update
    if hash? target and hash? first_arg
       target = process_hash_merge! target, first_arg
       env[target_var] = target
       return target
    end
  when :merge
    if hash? target and hash? first_arg
      return process_hash_merge(target, first_arg)
    end
  when :<<
    if string? target and string? first_arg
      target.value << first_arg.value
      env[target_var] = target
      return target
    elsif string? target and string_interp? first_arg
      exp = Sexp.new(:dstr, target.value + first_arg[1]).concat(first_arg[2..-1])
      env[target_var] = exp
    elsif string? first_arg and string_interp? target
      if string? target.last
        target.last.value << first_arg.value
      elsif target.last.is_a? String
        target.last << first_arg.value
      else
        target << first_arg
      end
      env[target_var] = target
      return first_arg
    elsif new_string? target
      env[target_var] = first_arg
      return first_arg
    elsif array? target
      target << first_arg
      env[target_var] = target
      return target
    else
      target = find_push_target(target_var)
      env[target] = exp unless target.nil? # Happens in TemplateAliasProcessor
    end
  when :first
    if array? target and first_arg.nil? and sexp? target[1]
      exp = target[1]
    end
  when :freeze
    unless target.nil?
      exp = target
    end
  when :dup
    unless target.nil?
      exp = target
    end
  when :join
    if array? target and target.length > 2 and (string? first_arg or first_arg.nil?)
      exp = process_array_join(target, first_arg)
    end
  when :!
    #  Convert `!!a` to boolean
    if call? target and target.method == :!
      exp = s(:or, s(:true).line(exp.line), s(:false).line(exp.line)).line(exp.line)
    end
  end

  exp
end

#process_case(exp) ⇒ Object


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# File 'lib/brakeman/processors/alias_processor.rb', line 832

def process_case exp
  if @ignore_ifs.nil?
    @ignore_ifs = @tracker && @tracker.options[:ignore_ifs]
  end

  if @ignore_ifs
    process_default exp
    return exp
  end

  branch_scopes = []
  was_inside = @inside_if
  @inside_if = true

  exp[1] = process exp[1] if exp[1]

  case_value = if node_type? exp[1], :lvar, :ivar, :call
    exp[1].deep_clone
  end

  exp.each_sexp do |e|
    if node_type? e, :when
      scope do
        @branch_env = env.current

        # set value of case var if possible
        if case_value and simple_when? e
          @branch_env[case_value] = e[1][1]
        end

        # when blocks aren't blocks, they are lists of expressions
        process_default e

        branch_scopes << env.current

        @branch_env = nil
      end
    end
  end

  # else clause
  if sexp? exp.last
    scope do
      @branch_env = env.current

      process_default exp[-1]

      branch_scopes << env.current

      @branch_env = nil
    end
  end

  @inside_if = was_inside

  branch_scopes.each do |s|
    merge_if_branch s
  end

  exp
end

#process_cdecl(exp) ⇒ Object

Constant assignments like BIG_CONSTANT = 234810983


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# File 'lib/brakeman/processors/alias_processor.rb', line 700

def process_cdecl exp
  if sexp? exp.rhs
    exp.rhs = process exp.rhs
  end

  if @tracker
    @tracker.add_constant exp.lhs,
      exp.rhs,
      :file => @current_file,
      :module => @current_module,
      :class => @current_class,
      :method => @current_method
  end

  if exp.lhs.is_a? Symbol
    match = Sexp.new(:const, exp.lhs)
  else
    match = exp.lhs
  end

  env[match] = get_rhs(exp)

  exp
end

#process_cvdecl(exp) ⇒ Object

Class variable assignment @@x = 1


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# File 'lib/brakeman/processors/alias_processor.rb', line 511

def process_cvdecl exp
  match = Sexp.new(:cvar, exp.lhs)
  exp.rhs = process(exp.rhs)
  value = get_rhs(exp)

  set_value match, value

  exp
end

#process_default(exp) ⇒ Object

Process a Sexp. If the Sexp has a value associated with it in the environment, that value will be returned.


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# File 'lib/brakeman/processors/alias_processor.rb', line 56

def process_default exp
  @exp_context.push exp

  begin
    exp.map! do |e|
      if sexp? e and not e.empty?
        process e
      else
        e
      end
    end
  rescue => err
    if @tracker
      @tracker.error err
    else
      raise err
    end
  end

  result = replace(exp)

  @exp_context.pop

  result
end

#process_defn(exp) ⇒ Object

Process a method definition.


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# File 'lib/brakeman/processors/alias_processor.rb', line 417

def process_defn exp
  meth_env do
    exp.body = process_all! exp.body
  end
  exp
end

#process_defs(exp) ⇒ Object

Process a method definition on self.


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# File 'lib/brakeman/processors/alias_processor.rb', line 437

def process_defs exp
  env.scope do
    set_env_defaults
    exp.body = process_all! exp.body
  end
  exp
end

#process_gasgn(exp) ⇒ Object

Global assignment $x = 1


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# File 'lib/brakeman/processors/alias_processor.rb', line 495

def process_gasgn exp
  match = Sexp.new(:gvar, exp.lhs)
  exp.rhs = process(exp.rhs)
  value = get_rhs(exp)

  if value
    value.line = exp.line

    set_value match, value
  end

  exp
end

#process_hash(exp) ⇒ Object


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# File 'lib/brakeman/processors/alias_processor.rb', line 604

def process_hash exp
  exp = process_default(exp)

  # Handle { **kw }
  if node_type? exp, :hash
    if exp.any? { |e| node_type? e, :kwsplat and node_type? e.value, :hash }
      kwsplats, rest = exp.partition { |e| node_type? e, :kwsplat and node_type? e.value, :hash }
      exp = Sexp.new.concat(rest).line(exp.line)

      kwsplats.each do |e|
        exp = process_hash_merge! exp, e.value
      end
    end
  end

  exp
end

#process_hash_merge(hash, args) ⇒ Object

Return a new hash Sexp with the given values merged into it.

args should be a hash Sexp as well.


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# File 'lib/brakeman/processors/alias_processor.rb', line 638

def process_hash_merge hash, args
  hash = hash.deep_clone
  hash_iterate args do |key, replacement|
    hash_insert hash, key, replacement
  end
  hash
end

#process_hash_merge!(hash, args) ⇒ Object

Merge values into hash when processing

h.merge! :something => “value”


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# File 'lib/brakeman/processors/alias_processor.rb', line 625

def process_hash_merge! hash, args
  hash = hash.deep_clone
  hash_iterate args do |key, replacement|
    hash_insert hash, key, replacement
    match = Sexp.new(:call, hash, :[], key)
    env[match] = replacement
  end
  hash
end

#process_helper_method(method_exp, args) ⇒ Object


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# File 'lib/brakeman/processors/alias_processor.rb', line 1004

def process_helper_method method_exp, args
  method_name = method_exp.method_name
  Brakeman.debug "Processing method #{method_name}"

  info = @helper_method_info[method_name]

  #If method uses instance variables, then include those and request
  #variables (params, etc) in the method environment. Otherwise,
  #only include request variables.
  if info[:uses_ivars]
    meth_env = only_ivars(:include_request_vars)
  else
    meth_env = only_request_vars
  end

  #Add arguments to method environment
  assign_args method_exp, args, meth_env


  #Find return values if method does not depend on environment/args
  values = @helper_method_cache[method_name]

  unless values
    #Serialize environment for cache key
    meth_values = meth_env.instance_variable_get(:@env).to_a
    meth_values.sort!
    meth_values = meth_values.to_s

    digest = Digest::SHA1.new.update(meth_values << method_name.to_s).to_s.to_sym

    values = @helper_method_cache[digest]
  end

  if values
    #Use values from cache
    values[:ivar_values].each do |var, val|
      env[var] = val
    end

    values[:return_value]
  else
    #Find return value for method
    frv = Brakeman::FindReturnValue.new
    value = frv.get_return_value(method_exp.body_list, meth_env)

    ivars = {}

    only_ivars(false, meth_env).all.each do |var, val|
      env[var] = val
      ivars[var] = val
    end

    if not frv.uses_ivars? and args.length == 0
      #Store return value without ivars and args if they are not used
      @helper_method_cache[method_exp.method_name] = { :return_value => value, :ivar_values => ivars }
    else
      @helper_method_cache[digest] = { :return_value => value, :ivar_values => ivars }
    end

    #Store information about method, just ivar usage for now
    @helper_method_info[method_name] = { :uses_ivars => frv.uses_ivars? }

    value
  end
end

#process_iasgn(exp) ⇒ Object

Instance variable assignment


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# File 'lib/brakeman/processors/alias_processor.rb', line 475

def process_iasgn exp
  self_assign = self_assign?(exp.lhs, exp.rhs)
  exp.rhs = process exp.rhs
  ivar = Sexp.new(:ivar, exp.lhs).line(exp.line)

  if self_assign
    if env[ivar].nil? and @meth_env
      @meth_env[ivar] = get_rhs(exp)
    else
      env[ivar] = get_rhs(exp)
    end
  else
    set_value ivar, get_rhs(exp)
  end

  exp
end

#process_if(exp) ⇒ Object

Sets @inside_if = true


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# File 'lib/brakeman/processors/alias_processor.rb', line 744

def process_if exp
  if @ignore_ifs.nil?
    @ignore_ifs = @tracker && @tracker.options[:ignore_ifs]
  end

  condition = exp.condition = process exp.condition

  #Check if a branch is obviously going to be taken
  if true? condition
    no_branch = true
    exps = [exp.then_clause, nil]
  elsif false? condition
    no_branch = true
    exps = [nil, exp.else_clause]
  else
    no_branch = false
    exps = [exp.then_clause, exp.else_clause]
  end

  if @ignore_ifs or no_branch
    exps.each_with_index do |branch, i|
      exp[2 + i] = process_if_branch branch
    end
  else
    # Translate `if !...` into `unless ...`
    # Technically they are different but that's only if someone overrides `!`
    if call? condition and condition.method == :!
      condition = condition.target
      exps.reverse!
    end

    was_inside = @inside_if
    @inside_if = true

    branch_scopes = []
    exps.each_with_index do |branch, i|
      scope do
        @branch_env = env.current
        branch_index = 2 + i # s(:if, condition, then_branch, else_branch)
        if i == 0 and array_include_all_literals? condition
          # If the condition is ["a", "b"].include? x
          # set x to "a" inside the true branch
          var = condition.first_arg
          previous_value = env.current[var]
          env.current[var] = safe_literal(var.line)
          exp[branch_index] = process_if_branch branch
          env.current[var] = previous_value
        elsif i == 1 and array_include_all_literals? condition and early_return? branch
          var = condition.first_arg
          env.current[var] = safe_literal(var.line)
          exp[branch_index] = process_if_branch branch
        else
          exp[branch_index] = process_if_branch branch
        end
        branch_scopes << env.current
        @branch_env = nil
      end
    end

    @inside_if = was_inside

    branch_scopes.each do |s|
      merge_if_branch s
    end
  end

  exp
end

#process_if_branch(exp) ⇒ Object


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# File 'lib/brakeman/processors/alias_processor.rb', line 894

def process_if_branch exp
  if sexp? exp
    if block? exp
      process_default exp
    else
      process exp
    end
  end
end

#process_iter(exp) ⇒ Object


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# File 'lib/brakeman/processors/alias_processor.rb', line 349

def process_iter exp
  @exp_context.push exp
  exp[1] = process exp.block_call
  if array_detect_all_literals? exp[1]
    return safe_literal(exp.line)
  end

  @exp_context.pop

  env.scope do
    call = exp.block_call
    block_args = exp.block_args

    if call? call and [:each, :map].include? call.method and all_literals? call.target and block_args.length == 2 and block_args.last.is_a? Symbol
      # Iterating over an array of all literal values
      local = Sexp.new(:lvar, block_args.last)
      env.current[local] = safe_literal(exp.line)
    else
      block_args.each do |e|
        #Force block arg(s) to be local
        if node_type? e, :lasgn
          env.current[Sexp.new(:lvar, e.lhs)] = Sexp.new(:lvar, e.lhs)
        elsif node_type? e, :kwarg
          env.current[Sexp.new(:lvar, e[1])] = e[2]
        elsif node_type? e, :masgn, :shadow
          e[1..-1].each do |var|
            local = Sexp.new(:lvar, var)
            env.current[local] = local
          end
        elsif e.is_a? Symbol
          local = Sexp.new(:lvar, e)
          env.current[local] = local
        elsif e.nil? # trailing comma, argument destructuring
          next # Punt for now
        else
          raise "Unexpected value in block args: #{e.inspect}"
        end
      end
    end

    block = exp.block

    if block? block
      process_all! block
    else
      exp[3] = process block
    end
  end

  exp
end

#process_lasgn(exp) ⇒ Object

Local assignment x = 1


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# File 'lib/brakeman/processors/alias_processor.rb', line 456

def process_lasgn exp
  self_assign = self_assign?(exp.lhs, exp.rhs)
  exp.rhs = process exp.rhs if sexp? exp.rhs
  return exp if exp.rhs.nil?

  local = Sexp.new(:lvar, exp.lhs).line(exp.line || -2)

  if self_assign
    # Skip branching
    env[local] = get_rhs(exp)
  else
    set_value local, get_rhs(exp)
  end

  exp
end

#process_masgn(exp) ⇒ Object

Multiple/parallel assignment:

x, y = z, w


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# File 'lib/brakeman/processors/alias_processor.rb', line 563

def process_masgn exp
  exp[2] = process exp[2] if sexp? exp[2]

  if node_type? exp[2], :to_ary and array? exp[2][1]
    exp[2] = exp[2][1]
  end

  unless array? exp[1] and array? exp[2] and exp[1].length == exp[2].length
    return process_default(exp)
  end

  vars = exp[1].dup
  vals = exp[2].dup

  vars.shift
  vals.shift

  # Call each assignment as if it is normal
  vars.each_with_index do |var, i|
    val = vals[i]
    if val

      # This happens with nested destructuring like
      #   x, (a, b) = blah
      if node_type? var, :masgn
        # Need to add value to masgn exp
        m = var.dup
        m[2] = s(:to_ary, val)

        process_masgn m
      else
        assign = var.dup
        assign.rhs = val
        process assign
      end
    end
  end

  exp
end

#process_op_asgn1(exp) ⇒ Object

Assignments like this x ||= 1


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# File 'lib/brakeman/processors/alias_processor.rb', line 648

def process_op_asgn1 exp
  target_var = exp[1]
  target_var &&= target_var.deep_clone

  target = exp[1] = process(exp[1])
  index = exp[2][1] = process(exp[2][1])
  value = exp[4] = process(exp[4])
  match = Sexp.new(:call, target, :[], index)

  if exp[3] == :"||"
    unless env[match]
      if request_value? target
        env[match] = match.combine(value)
      else
        env[match] = value
      end
    end
  else
    new_value = process s(:call, s(:call, target_var, :[], index), exp[3], value)

    env[match] = new_value
  end

  exp
end

#process_op_asgn2(exp) ⇒ Object

Assignments like this x.y ||= 1


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# File 'lib/brakeman/processors/alias_processor.rb', line 676

def process_op_asgn2 exp
  return process_default(exp) if exp[3] != :"||"

  target = exp[1] = process(exp[1])
  value = exp[4] = process(exp[4])
  method = exp[2]

  match = Sexp.new(:call, target, method.to_s[0..-2].to_sym)

  unless env[match]
    env[match] = value
  end

  exp
end

#process_or_simple_operation(exp) ⇒ Object

If possible, distribute operation over both sides of an or. For example,

(1 or 2) * 5

Becomes

(5 or 10)

Only works for strings and numbers right now.


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# File 'lib/brakeman/processors/alias_processor.rb', line 1248

def process_or_simple_operation exp
  arg = exp.first_arg
  return nil unless string? arg or number? arg

  target = exp.target
  lhs = process_or_target(target.lhs, exp.dup)
  rhs = process_or_target(target.rhs, exp.dup)

  if lhs and rhs
    if same_value? lhs, rhs
      lhs
    else
      exp.target.lhs = lhs
      exp.target.rhs = rhs
      exp.target
    end
  else
    nil
  end
end

#process_or_target(value, copy) ⇒ Object


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# File 'lib/brakeman/processors/alias_processor.rb', line 1269

def process_or_target value, copy
  if string? value or number? value
    copy.target = value
    process copy
  else
    false
  end
end

#process_safely(src, set_env = nil, current_file = @current_file) ⇒ Object

This method processes the given Sexp, but copies it first so the original argument will not be modified.

set_env should be an instance of SexpProcessor::Environment. If provided, it will be used as the starting environment.

This method returns a new Sexp with variables replaced with their values, where possible.


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# File 'lib/brakeman/processors/alias_processor.rb', line 46

def process_safely src, set_env = nil, current_file = @current_file
  @current_file = current_file
  @env = set_env || SexpProcessor::Environment.new
  @result = src.deep_clone
  process @result
  @result
end

#process_scope(exp) ⇒ Object

Process a new scope.


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# File 'lib/brakeman/processors/alias_processor.rb', line 402

def process_scope exp
  env.scope do
    process exp.block
  end
  exp
end

#process_svalue(exp) ⇒ Object

This is the right hand side value of a multiple assignment, like `x = y, z`


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# File 'lib/brakeman/processors/alias_processor.rb', line 694

def process_svalue exp
  exp.value
end

#raise?(exp) ⇒ Boolean

Returns:

  • (Boolean)

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# File 'lib/brakeman/processors/alias_processor.rb', line 1199

def raise? exp
  call? exp and exp.method == :raise
end

#replace(exp, int = 0) ⇒ Object


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# File 'lib/brakeman/processors/alias_processor.rb', line 82

def replace exp, int = 0
  return exp if int > 3

  if replacement = env[exp] and not duplicate? replacement
    replace(replacement.deep_clone(exp.line), int + 1)
  elsif tracker and replacement = tracker.constant_lookup(exp) and not duplicate? replacement
    replace(replacement.deep_clone(exp.line), int + 1)
  else
    exp
  end
end

#same_value?(lhs, rhs) ⇒ Boolean

Return true if lhs == rhs or lhs is an or expression and rhs is one of its values

Returns:

  • (Boolean)

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# File 'lib/brakeman/processors/alias_processor.rb', line 1107

def same_value? lhs, rhs
  if lhs == rhs
    true
  elsif node_type? lhs, :or
    lhs.rhs == rhs or lhs.lhs == rhs
  else
    false
  end
end

#self_assign?(var, value) ⇒ Boolean

Returns:

  • (Boolean)

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# File 'lib/brakeman/processors/alias_processor.rb', line 1117

def self_assign? var, value
  self_assign_var?(var, value) or self_assign_target?(var, value)
end

#self_assign_target?(var, value) ⇒ Boolean

Return true for x = x.blah

Returns:

  • (Boolean)

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# File 'lib/brakeman/processors/alias_processor.rb', line 1130

def self_assign_target? var, value
  target = top_target(value)

  if node_type? target, :lvar, :ivar
    target = target.value
  end

  var == target
end

#self_assign_var?(var, value) ⇒ Boolean

Return true if for x = blah or @x = blah

Returns:

  • (Boolean)

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# File 'lib/brakeman/processors/alias_processor.rb', line 1122

def self_assign_var? var, value
  call? value and
  value.method == :+ and
  node_type? value.target, :lvar, :ivar and
  value.target.value == var
end

#set_value(var, value) ⇒ Object

Set variable to given value. Creates “branched” versions of values when appropriate. Avoids creating multiple branched versions inside same if branch.


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# File 'lib/brakeman/processors/alias_processor.rb', line 1214

def set_value var, value
  if node_type? value, :if
    value = value_from_if(value)
  elsif node_type? value, :case
    value = value_from_case(value)
  end

  if @ignore_ifs or not @inside_if
    if @meth_env and node_type? var, :ivar and env[var].nil?
      @meth_env[var] = value
    else
      env[var] = value
    end
  elsif env.current[var]
    env.current[var] = value
  elsif @branch_env and @branch_env[var]
    @branch_env[var] = value
  elsif @branch_env and @meth_env and node_type? var, :ivar
    @branch_env[var] = value
  else
    env.current[var] = value
  end
end

#simple_when?(exp) ⇒ Boolean

Returns:

  • (Boolean)

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# File 'lib/brakeman/processors/alias_processor.rb', line 825

def simple_when? exp
  node_type? exp[1], :array and
    not node_type? exp[1][1], :splat, :array and
    (exp[1].length == 2 or
     exp[1].all? { |e| e.is_a? Symbol or node_type? e, :lit, :str })
end

#too_deep?(exp) ⇒ Boolean

Returns:

  • (Boolean)

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# File 'lib/brakeman/processors/alias_processor.rb', line 925

def too_deep? exp
  @or_depth_limit >= 0 and
  node_type? exp, :or and
  exp.or_depth and
  exp.or_depth >= @or_depth_limit
end

#top_target(exp, last = nil) ⇒ Object

Returns last non-nil target in a call chain


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# File 'lib/brakeman/processors/alias_processor.rb', line 1141

def top_target exp, last = nil
  if call? exp
    top_target exp.target, exp
  elsif node_type? exp, :iter
    top_target exp.block_call, last
  else
    exp || last
  end
end

#value_from_case(exp) ⇒ Object


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# File 'lib/brakeman/processors/alias_processor.rb', line 1173

def value_from_case exp
  result = []

  exp.each do |e|
    if node_type? e, :when
      result << e.last
    end
  end

  result << exp.last if exp.last # else

  result.reduce do |c, e|
    if c.nil?
      e
    elsif node_type? e, :if
      c.combine(value_from_if e)
    elsif raise? e
      c # ignore exceptions
    elsif e
      c.combine e
    else # when e is nil
      c
    end
  end
end

#value_from_if(exp) ⇒ Object


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# File 'lib/brakeman/processors/alias_processor.rb', line 1151

def value_from_if exp
  if block? exp.else_clause or block? exp.then_clause
    #If either clause is more than a single expression, just use entire
    #if expression for now
    exp
  elsif exp.else_clause.nil?
    exp.then_clause
  elsif exp.then_clause.nil?
    exp.else_clause
  else
    condition = exp.condition

    if true? condition
      exp.then_clause
    elsif false? condition
      exp.else_clause
    else
      exp.then_clause.combine(exp.else_clause, exp.line)
    end
  end
end